you guys must be the worst robbers in the city. two days out of jail, and you're back again? what's your story this time? >> both: i don't know nothing. >> thirty days. >> going to be good. >> game theory forces us to think about choices, strategies, and payoffs. not in a way that reduces us to easily predictable individuals caught in a grid, but in relation to the activity of others. in the iterated prisoner's dilemma, it would be great if everybody played a pure cooperate strategy, since this is what would give the greatest payoff. but the temptation to cheat, to buck the system, is there. maybe that's the point, that math goes beyond our instincts. our instincts are often wrong, and mathematics, carefully considered, can be a guide beyond the gut. with mathematics, we can show that a common behavior that we might consider foolish can in fact make considerable sense. sometimes these "odd" strategies are informally encoded in cultural norms, like the golden rule. at its heart, that's perhaps really what game theory is about: the evolution of these rules and norms or institut